EU/3/13/1107

On 12 March 2013, orphan designation (EU/3/13/1107) was granted by the European Commission to TMC Pharma Services Ltd, United Kingdom, for recombinant adeno-associated viral vector containing the human retinoschisin gene for the treatment of X-linked juvenile retinoschisis.

What is X-linked juvenile retinoschisis?

X-linked juvenile retinoschisis is a hereditary eye disorder in which patients are unable to make a protein, retinoschisin, needed for normal function of the retina (the light-sensitive layer at the back of the eye). Typically, the disease damages cells in the central part of the retina called the macula, which is responsible for sharp central vision required for detailed tasks such as reading, driving and recognising faces. Rarely, other complications affecting vision develop, such as retinal detachment, vitreous haemorrhage (leakage of blood vessels in the retina), glaucoma (increased pressure in the eye), cataracts (clouding of the lens) and increased formation of blood vessels in the eye.

Because the condition is caused by a defective gene on the X chromosome it occurs almost exclusively in males, who only have one copy of this chromosome in their cells; in females a second, undamaged copy can compensate for the defective gene.

The condition is long-term debilitating due to the progressive loss of visual acuity and the higher risk of developing visual complications.

What is the estimated number of patients affected by the condition?

At the time of designation, X-linked juvenile retinoschisis affected approximately 0.4 in 10,000 people in the European Union (EU). This was equivalent to a total of around 20,000 people*, and is below the ceiling for orphan designation, which is 5 people in 10,000. This is based on the information provided by the sponsor and the knowledge of the Committee for Orphan Medicinal Products (COMP).

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*Disclaimer: For the purpose of the designation, the number of patients affected by the condition is estimated and assessed on the basis of data from the European Union (EU 27), Norway, Iceland and Liechtenstein. This represents a population of 509,000,000 (Eurostat 2013).

What treatments are available?

At the time of designation, no satisfactory methods were authorised in the EU to treat X-linked juvenile retinoschisis.

How is this medicine expected to work?

The medicine is made up of a virus that contains normal copies of the gene responsible for producing retinoschisin. When injected into the patient’s eyes, it is expected that the virus will carry this gene into retinal cells, so that they can produce retinoschisin. This is expected to enable retinal cells to work properly, thereby treating the symptoms of the disease.

The type of virus used in this medicine (‘adeno-associated virus’) does not cause disease in humans.

What is the stage of development of this medicine?

At the time of submission of the application for orphan designation, the evaluation of the effects of the medicine in experimental models was ongoing.

At the time of submission, no clinical trials with the medicine in patients with X-linked juvenile retinoschisis had been started.

At the time of submission, the medicine was not authorised anywhere in the EU for X-linked juvenile retinoschisis. Orphan designation of the medicine had been granted in the United States for X-linked juvenile retinoschisis.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 6 February 2013 recommending the granting of this designation.

Opinions on orphan medicinal product designations are based on the following three criteria:

• the seriousness of the condition;
• the existence of alternative methods of diagnosis, prevention or treatment;
• either the rarity of the condition (affecting not more than 5 in 10,000 people in the EU) or insufficient returns on investment.

Designated orphan medicinal products are products that are still under investigation and are considered for orphan designation on the basis of potential activity. An orphan designation is not a marketing authorisation. As a consequence, demonstration of quality, safety and efficacy is necessary before a product can be granted a marketing authorisation.

The Committee for Orphan Medicinal Products reviews the orphan designation of a product if it is approved for marketing authorisation.